Precision chuck



June 11, 1946. H L SCHUSl-ER `2,401,971

PRECISION CHUCK Filed Aug. 24, 1944 2 Sheets-Sheet 1` Jza @Z4- INVENTUR AT1-neuem.

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June 11, 1946- H. l. scHUsTER 2,401,971

PRECISION GHUCK Filed Aug. 424,' 1944 2 sheetsheet 2 vinyl-HES? y n;

I7 .Je JZ @j l fig IN VENT'QE A51-Tonne Patented June 11, 1946 UNITED STATES PATENTy OFFICE PRECISION CHUCK Harry I. Schuster, Milwaukee, Wis.

Application August 24, 1944, Serial No. 550,914

v Claims. 1

precision chucks.

The invention has particular reference to the type of chuck in which a number of jaws are simultaneously actuated radially to and from Work-engaging jaws, as by a pneumatic cylinder and piston. In such devices, a precise adjustment of the respective work-engaging jaws is essential in order that the several jaws may simultaneously engage and release the work and precisely support it exactly on center.

It is the primary object of the present invention to provide novel and improved means for adjusting the work-engaging jaw of such a chuck with respect to its carrier or master jaw.

The objects of the invention will be more specifically apparent to those skilled in the art on the basis of a study of the following disclosure.

In the drawings:

Figure 1 is an axial section through a chuck embodying the invention.

Fig. 2 is Va detail View in perspective of the master jaw and the work-engaging jaw, and the key by which accurate adjustment of the relation between these parts is eiect'ed.

Fig. 3 is a front elevation of the assembly shown in Fig. 1, portions of the Work-engaging jaws being broken away to expose the means for adjustment.

Fig. 4 is a fragmentary detail section on the line 4-4 of Fig. 1'.,

Fig. 5 is a fragmentary detail view taken in section on the line 5-5 of Fig. 1

Like parts are identified by the same reference characters throughout the several views.

Many of the parts shown are conventional and, hence, will be but brieiiy described. There is illustrated at 6 a work spindle upon which the chuck head 'I is mounted in the usual manner. The chuck head I provides guideways in which the carriers or master jaw elements 8 are radially adjustable. In the device illustrated, three such carriers are shown. They are simultaneously reciprocated radially along their respective guideways by means of bellcranks within the head, one of which is illustrated at 9, pivoted for oscillation upon a pintle I0 and provided with an arm II engaged inthe notch I2 of the carrier or master jaw 8, shown in Fig. l.

The longer arm of the bellcrank 9 extends centrally into engagement with notch I3 of the slide I4, which is reciprocable axially of the spinview taken in dle 6, under the control of a threaded rod I5,

which may be connected with a suitable pneumatically operated piston (not shown). For adjustments affecting the range of operation of all of the several jaws 8, a tubular nut i6 is provided in threaded engagement with the end of the rod I5, such nut having` a slotted head I'I, accessible through the center of the chuck for adjustment of the nut. The head Il sets against a shoulder at I8 in the sleeve portion I9 of the bellcrank actuator I4. A collar 20 is held by the set screw 2l on the nut I6 in thrust engagement with the end of the sleeve I9. A spring-pressed detent, including a b all 22, selectively engages in pockets 22' in the ends of the sleeve I9 in the various positions to which the nut may be adjusted.

The outer face of each of the master jaws or carrier members 8 is provided with a guideway comprising a T-slot 23 for the spline 24 of the Work-engaging jaw elements 25. Thus, any adjustment between the work-engaging jaw 25 and the` master jaw 8 must be eiected solely in a radial direction. v

At either side of the T-slotY 23, the `outer face of the master jaw is provided with a series of serrations or threads 26 inclined obliquely with reference to the radial T-slot 23. A key member 38 disposed transversely of the face of the master jaw member 8 has complementary obliquely disposed teeth meshing with the teeth of the master jaw. The key member 30 is preferably at right angles to the radius of the'chuck. The key member 38 may be applied to the face of the master jaw at any desired point to mesh with any selected teeth thereon. The pitch of the teeth is such that, by moving the key member from right to left across the face of the master jaw, it maybe made to receive radial movement equal to the displacement or pitch distance between successive teeth. The adjustment of the key member 30 transversely with the master jaw is effected and maintained by set screws 3I, 32, threaded in the lugs 33, 34, which are bolted to the key member and whichv bear against the side faces of the master jaw, as clearly shown in Figs. 2 and 4.

The key member its into a transverse guideway 35 on the false jaw 25 so that any movement of the key member in a direction radial of the chuck is imparted to the work-engaging jaw 25 to cause such jaw to move laterally of the chuck. One or more clamping bolts 36 hold the false jaw releasably in adjustment. Each clamping bolt has a nut 31 in the T-slot 23. A separate bolt 38 preferably connects each work-engaging jaw 25 to its respective key 30, the key being slotted to 

